Compass-indicating apparatus.



No. 810,866. PATENTED JAN. 23, 1906.

. B. V. HOW. COMPASS INDIGATING APPARATUS.

APPLICATION FILED SEPT. 19. 1905.

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L4 z m 5V 0' UNITED STATES PATENT OFFICE.

BENJAMIN VARNUM HOW, OF WESTON, MASSACHUSETTS, ASSIGNOR TO ARBECAM NAUTICAL INSTRUMENT CO., OF BOSTON, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

Specification of IQette'rs Patent.

' Patented Jan. 23, 1906.

Application filed September 19, 1905. Serial No. 279,169.

- To all whom it may concern:

' 'usual.

said telescope.- A deviation-corrector'15 16 Be it known that I, BENJAMIN VARNUM HOW, of Weston, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Compass-Indicating Apparatus, of which the following is a specification.

This invention is in the nature of improvement upon the so-called Arbec'arn alidade or compass-indicator, my improvements cooperating with said instrument to perfect its action and increase its general utility. These improvements relate to an adjustable circular triangulation-platelying fiat upon the compass-dial and having the effect of dividing said dial when desired into three hundred and sixty degrees instead of'one hundred and twenty-eight nautical points, also to an azimuth-tube parallel with'and mounted on the main telescope for observing the;

sun at midday or otherwise, also to a concave mirror adjustably mounted near the eyepiece of the telescope or azimuth-tube and. adapted to throw a pencil of light along the exterior of the barrel and on a glittering point thereon .to facilitate observations, as -will be explained, and to a spirit-level transversely arranged on the telescopeor azimuthtube of the alidade to denote whenthe ship is I -dev1ce, shown flattened at top and secured at on an even keel.

with my improvements and shown mounted on a binnacle partly broken away. Figs. 2,

3, and 4 are enlarged details, Fig. 2 being a top plan showing a portion of the'telescope and parts mounted thereon, Fig. 3 a transverse section on line 3 3 of Fig. 1, and Fig. 4

an elevation of the mirror,its arm being in section on line 4 4 of Fig. 2.

The binnacle 10 will be of any approved form inclosing the'compass 11, suspended as The top of the binnacle supports a rotatable vertical shaft 12, made in sections and located immediately over the center of the compass-dial. Such shaft carries at top a horizontally-pivoted si hting-tube or telesco e 13 and at foot aradial pointer 14, norma ly maintained in the'same radial plane as projects horizontally from said shaft at an intermediate oint. I make no claim to these several evices other than in combination with the features of my invention hereinafter described.

The triangulation-plate 17' is a flat circular disk, preferably of metal or glass, graduated marginally in three hundred and sixty degrees and adapted to rest frictionally on the central portion of the compass-dial beneath the radial pointer 14, leaving uncovered the margin of the dial and the usual circle of letters denoting points of the compass. This plate has a central perforation to receive the extremity of shaft 12 or the downwardly-extending tip of the short vertical stem" on which the indicating-pointer is pivoted. Said stem fits loosely within, but rotates with, the hollow lower end of shaft 12, as heretofore, and serves as an axis about which the plate 17 may be moved adjustably with, relation to the compass bythe operators finger without disturbingthe indicator or pointer 14. Thus the zero or north mark can be set atany point on the margin of the compass-dial, and y use of the alidade the distance or angle of vvisibleobjects can be ascertained by triangu- -lation.

The altitude-plate 20 is a disk or ring-like its upper edge to the side of the telescope 13 by clamps or screws 21 in such manner that ii'tscenter coincides with the prolonged hori -zontal stemof the screw 22, by which the telescope is secured to the top of shaft 12. The lower portion of said plate is arc shaped, preferably of semicircular form, and is beveled and graduated marginally in degrees, counting each way from zero at a central point thereon. A vernier-plate 23, constituting an index-point and support or steadying' device for the edge of the altitude-plate, is fixed on or connected to the side of the vertical shaftto indicate in degrees on the marginal altitude-scale the inclination up ordown of the telescope. When there is no inclination, the zero-point on said scale and the index or zero polnt on vernier 23 will meet or coincide. Tilting the telescope up or' down moves the altitude-plate relatively to the Vernier or index point andshows the angle of the sun or any given object sighted through the instrument. Approximate distances of landmarks, vessels, or like objects can thus be observed and noted.

The upper part of shaft 12 is formed of two concentric tubes, as shown in Fig. 3, the telescope 13 being pivoted to the top of the inner tube, as in the Arbecam instrument. I therefore connect the Vernier-plate 23 also to the inner tube by a screw 24, which passes through a short transverse slot 25 in the outer tube 12, so that the proper relation of the fixed to and parallel with the telescope 13 I and provided with a colored lens of suitableshade. Theeyepiece is provided with a centrally-perforated transverse disk, and when the sun is seen through this minute perforation, which is at the axis of tube 27, the main telescope will point directly to the sun, and the indicator or radial pointer 14 will denote on the compass-dial the exact vertical plane of the sun. The colored lensis mounted in a removable cap 26 at the end opposite the eyepiece. Thus the lens may be removed when the sun is obscured. 7

For greater convenience. in the sun for midday observations I provide a small concave mirror 28, hung in a yoke 29, erected on a swinging arm 30, which is pivot.-

ed to the under side of telescope 13, as'in Fig.

1, so that it can be partially folded alongside of the instrument or swung into trans-, verse position at the ends of tubes 13 'and25,

as shown. A suitable stop 31 checks this swinging movement of arm 30 at the proper point. The supporting-stem of yoke 29 is shown in Fig. 4 as formed of connected sections, shouldered, as at 32, to permit partial oscillation and form a stop when the mirror is in proper transverse position. When thus transversely placed and tilted on its bearings, said mirror is adapted to throw a converging pencil of light longitudinally along the top of the azimuth-tube, as indicated in Fig. 2. At the exact focus of such reflected rays I locate a pin-head protuberance of burnished metal 33, which seems to blaze with light when the concentrated rays strike it, indicating instantly that the sun is in the direct line of vision through either tube. The

mirror may then be swung aside and the ob-.

servation taken. In this operation the small mirror receives the suns rays freely and converges them on the barrel of the telescope or azimuth-tube at a defined point when such tube is axially in line with the sun, this method being vastly more comfortable and speedy than the effort to obtain such axial position bylooking obliquely upward through the tubes.

' To indicate the moment when the ship is on an even keel, my instrument is also furnished with a small s irit-level 34, arranged transversely of the te escope-barrel and preferably mounted on a metal base brazed crosswise on the azimuthtube, where it may be readily noted while taking observations. The various devices, so far as practicable, should be observed simultaneously by glancing from the light-ray on the azimuth-tube to the bubble in the level, and thence to the pointer on the triangulation-plate, at once noting the degree-mark thereon.

I claim as my invention 1. In compass-indicating apparatus, a rotatable vertical shaft supported on the binnacle-top and carrying, terminally, a sighting device anda radial indicator, in combination "with a circular triangulation-plate perforated centrally, graduated marginally in degrees and maintained frictionally and adjustably on the compass-dial beneathsaid indicator,

and with a reduced downward extension of said shaft serving in such perforation, as an axis of rotation for said plate, substantially as set forth.

2. In compass-indicating apparatus, a rotatable vertical shaft supported on the binnacle and carrying, terminally, a sighting device and a radial indicator, normally maintained in the same vertical plane, in combination with an azimuth-tube fixed on and parallel with the sighting device, such tube a'v'ing terminally a perforated eyepiece and a removable end cap carrying a colored lens, substantially as and for the purpose set forth.

3. In compass-indicating apparatus, a rotatable sectional shaft supported vertically on the binnacle, a sighting device and radial indicator connected terminally to said shaft, and a supplementary azimuth-tube fixed on said device in the same vertical plane, in combination with a concave mirror adjustably mounted on a swinging arm and adapted to converge the suns rays at a defined point on said tube, substantially as and for the purpose set forth.

4. In compass-indicating apparatus, a rotatable sectional shaft supported vertically on the binnacle, a sighting device and radial indicator connected terminally to said shaft, and a supplementary azimuth-tube fixed on the sighting device and parallel with the axis thereof, in combination with a concave mir- In testimony whereof I have affixed my ror mounted in bearings in a yoke carried on signature in presence of two witnesses. a swinging arm pivoted to the sighting de- BENJAMIN VARNUM HOV vice and furnished with a suitable stop, and

with a spirit-level arranged transversely of Witnesses:.

the sighting device, to denote when the ship A. H. SPENCER, is on an even keel, substantially as set forth. H. W. LADD. 

